Autochangers are devices that store media pieces in a library, read data stored on the media pieces, and write data onto the media pieces. The media pieces are stored in a plurality of storage slots, sometimes referred to as a library, which is located within the physical structure of the autochanger. At least one media "player" or "drive" is also located within the physical structure of the autochanger and serves to read and write data from and to the media pieces. A media handling device, often referred to herein simply as a picker, is located within the autochanger and serves to transport the media pieces between the library and the media player.
Autochangers may be adapted to operate with several different media formats, thus, "media pieces" may comprise optical discs, magnetic discs, and magnetic tapes, e.g., digital linear tapes, CD's etc. The digital linear tape is a common media format used in autochangers. A digital linear tape is a magnetic linear tape that is stored within a cartridge. The cartridge has a door that, when opened, exposes a leader portion of the tape which is located at a predetermined position relative to the cartridge. When the cartridge is placed inside the media player, the media player opens the door, grabs the leader and feeds the tape across a read/write head and to a pick up reel. When the tape is no longer required to be located in the media player, the media player rewinds the tape into the cartridge so that the leader is accessible for the next time the cartridge is used. If the leader is not located in the predetermined position, the media player will be unable to use the tape because it will not be able to feed the tape through the media player.
The library portion of an autochanger may comprise a removable magazine that is used to store media pieces. The magazine typically has a plurality of holding locations or slots adapted to hold the media pieces. A user places the media pieces into the holding locations in the magazine and then places the magazine into the library portion of the autochanger. When a specific media piece is required to be transported from the magazine to the media player, the picker extracts the media piece from the library, moves it to the media player, and inserts it into the media player. Likewise, when a media piece is no longer required in the media player, the picker reverses the above-described procedure and transports the media piece from the media player to the magazine. The autochanger tends to be a very compact unit, therefore, the picker typically comes in close proximity to the media pieces located in the magazine as it moves throughout the autochanger.
The media pieces are secured in the holding locations in order to keep them from inadvertently slipping out of the magazine. The user may, as an example, inadvertently tilt a magazine that is filled with media pieces. If the media pieces are not secured, they may fall out of the magazine and become damaged. In the case of a digital linear tape, the leader portion of the tape may become dislodged from its aforementioned predetermined position to a position where it is inaccessible by the media player. This will render the digital linear tape unusable by the autochanger because the tape will not be able to be fed through the media player.
Unsecured media pieces may also become dislodged from the magazine when the magazine is placed into the library portion of the autochanger. The user of the autochanger may, as an example, tilt the magazine as it is being placed into the autochanger, which may result in media pieces becoming dislodged from their respective holding locations. In another example, the user may transport the autochanger that has been loaded with media pieces. If the user transports the autochanger and inadvertently collides the autochanger with another object, the media pieces may become dislodged from their respective holding locations. In the case of either of the above-described situations, a media piece will be located at an improper location inside of the autochanger. When the picker moves within the autochanger, it may impact an improperly located media piece, which will likely result in damage to the components comprising the autochanger and the media piece.
As described above, there are two circumstances that may cause the media pieces to become dislodged from the magazine. The first circumstance is by the user inadvertently tilting the magazine. This may cause the media pieces to fall to a floor and become damaged. The second circumstance is if the user tilts the magazine as it is being loaded into the autochanger or causes the autochanger to strike an object. This may cause the media pieces to be located in the path of the picker, which may damage the autochanger or the picker. A detent mechanism may be used in the magazine in order to secure the media pieces within the magazine. It has been found that a detent mechanism must apply a greater force to keep the media pieces secured when the magazine is tilted external to the autochanger than to keep the media pieces from becoming dislodged within the autochanger.
The force associated with the detent mechanism requires that the picker apply a substantial force to the media pieces in order to remove them from the magazine. Overcoming this substantial force typically requires that the picker exert a force of between two and three pounds on the media pieces. This force has been found to be the greatest force that the picker is required to exert.
Overcoming this securing force requires that the picker use substantially strong components and consume significant power. For example, the picker is required to operate a servo mechanism that is capable of overcoming the securing force and that will not wear when it overcomes the securing force. This requires the use of a heavy and generally expensive servo motor and other components that comprise the servo mechanism. Furthermore, the servo motor must draw a significant amount of power from the autochanger in order to overcome the securing force, which requires that the autochanger be provided with a power supply that is capable of delivering relatively high power to the picker. This may significantly increase the size, cost, and weight of the autochanger.
Therefore, a need exists for a magazine that is capable of securing media pieces within the magazine, while allowing the media pieces to be extracted by an application of a minimal force from the picker.